1. Field of the Invention
The present invention relates generally to containers that include an internal chemical-based module that heats or, alternatively, cools the material, such as a food, beverage, medicine, or the like, in the surrounding container.
2. Description of the Related Art
Containers may have integral modules for warming materials in the container, such as Japanese sake, coffee, or soup. Examples of such self-heating containers are disclosed in U.S. Pat. Nos. 5,461,867 and 5,626,022, issued to Scudder et al. Such containers typically include an outer can or body, in which the food or beverage is sealed, and an inner can orthermic module that contains two chemical reactants that are stable when separated from one another but, when they mix in response to actuation of the thermic module by a user, produce an exothermic reaction or, alternatively, an endothermic reaction and thereby heat or cool the contents of the container.
The heating or cooling module (thermic module) is typically attached at one end of the cylindrical container body, and the elongated cylindrical reaction chamber portion of the module extends into the container body. This elongated portion functions as both a chamber in which to contain the reaction and a heat-exchanger for transferring heat between it and the surrounding contents of the container body. The thermic module has two chambers, each of which contains one of the chemical reactants, separated by a breakable barrier such as metal foil. Typically, one of the reactants is a liquid, and the other is in a powdered or granular solid form. Calcium oxide and water are examples of two reactants known to produce an exothermic reaction in such containers to heat the contents. Other combinations of reactants are known to produce endothermic reactions to cool the container contents. A cap containing the liquid reactant is disposed in the end of the thermic module attached to the container body. At one end of the cap is an actuator button that a user may depress to initiate the heating or cooling. The barrier seals the other end of the cap. The cap has a pushrod or similar prong-like member that extends from the actuator button nearly to the barrier. Depressing the actuator button forces the prong into the barrier, puncturing it and thereby allowing the liquid reactant to flow into the solid reactant in the reaction chamber. The heat produced by the resulting exothermic reaction (or, alternatively, used by a resulting endothermic reaction) is transferred between the reaction chamber of the thermic module and the contents of the container body by conduction. The elongated portion of the module body that defines the reaction chamber may be fluted or pleated to promote such heat conduction. Exothermic reactions also typically generate a gas and/or steam, which is allowed to escape through vents in the end of the container. The user inverts the container and, when the contents have reached the desired temperature, consumes the contents. The second end of the container body has a seal or closure, such as conventional beverage can pull-tab or pop-top, that may be opened and through which the user may consume the heated or cooled contents.
Instructions printed on the container may advise the user to wait some period of time, such as 30 seconds, before inverting the container, because all of the water or other liquid reactant may not have drained through the puncture in the barrier into the reaction chamber if the user inverts the container too soon after actuating it. After inversion, any water remaining in the module cap behind the punctured barrier may not completely mix with the solid reactant because, while water can flow relatively unimpeded through the puncture, the solid reactant can not.
A potential problem is that most persons have difficulty judging the period of time specified in the container instructions. Many persons erroneously believe they can accurately judge when 30 seconds or a similar time period has elapsed without the aid of a clock or wristwatch and, consequently, do not bother to use one. Also, typical users of self-heating beverage containers are those who may be out of doors, on the go, or otherwise do not have convenient and immediate access to a timepiece. It would be desirable to eliminate the need for a user to wait a specified period of time before inverting a self-heating container of the type described above. These problems and deficiencies are clearly felt in the art and are solved by the present invention in the manner described below.